New empirical models of the ion temperature and ion composition

Description of accurate ion temperature (Ti) and composition in the upper ionosphere, topside ionosphere and plasmasphere is very important for understanding of thermal balance and the propagation of radio waves in these regions. We present results of our effort in development of new models of the ion temperature and ion composition primarily intended for improvement of the International Ionosphere Reference (IRI) model. For the ion temperature we have re-examined ion temperature data from older satellites and combined them with newly available data from DMSP, C/NOFS, and others (primarily from SPDF: https://spdf.gsfc.nasa.gov/pub/data/) into a unified data-base comprising in total Ti data from 17 satellites. This data-base has been used for the development of a new global empirical model of Ti. The model includes variations with solar activity. The solar activity variations of Ti are represented by a correction term of the Ti global pattern. Two versions of this term were developed - one with lower resolution using measured data and another with higher resolution with assistance of the theoretical FLIP model. At altitudes above 1000 km the ion temperature is merged into the electron temperature using calculations from a comprehensive ionosphere-plasmasphere model. Our improved global empirical model of ion composition is based on the TBT-15 model, which includes an improved description of the dependence of ion composition on solar activity and it is included in the latest version of the IRI model (2016). The improved version of the model includes an adjustment of the upper transition height that serves as an additional anchor point and it is based on a simple mathematical operation. Global models of the upper transition height from O⁺ to H⁺, which were also developed for this purpose are based on large data sets of vertical electron density profiles from ISIS, Alouette and FORMOSAT-3/COSMIC. We also discuss possible extension of this model into the plasmasphere using DE-1 RIMS data. We present validations of these models by comparisons with recent measurements from another sources especially from the incoherent scatter radars.